Blow moulding machine with arrangement for cleaning the blow mould

ABSTRACT

An apparatus for transforming plastic preforms into containers, includes at least one blow mould which forms a cavity, inside which the plastic preforms can be transformed into containers. The apparatus includes an opening and closing mechanism for opening and closing the blow mould, and a cleaning device for cleaning regions of the blow mould. The cleaning device includes at least a first cleaning element for cleaning an inner wall of the blow mould, which cleaning element is arranged at least at times outside the blow mould.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.12/853,162, filed Aug. 9, 2010, which is entirely incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to apparatuses for transforming plasticpreforms into plastic containers, and in particular to blow mouldingmachines. Such blow moulding machines have long been known from theprior art. They usually comprise a blow mould, inside which the plasticpreforms are expanded through the application of pressure to formplastic containers. During this stretch-blow moulding of plasticcontainers, so-called oligomers, i.e. short-chain molecules or foreignsubstances, are excreted onto the blow mould from the plastic of theplastic preforms. The surface of these blow moulds therefore becomesdull and in the extreme case rough as it becomes increasingly soiled.However, this has negative effects on the bottle quality, since this maylead to the situation whereby the bottle appearance may become cloudy onaccount of the dull blow moulds or else the cooling on the mould surfaceis reduced as a result of the roughness.

Since both of these problems are unacceptable, the blow moulds must becleaned and usually polished at regular intervals. Particularly highdegrees of soiling by oligomers occur when working with high mouldtemperatures for process reasons (e.g. in the case of hot fillprocesses), since soiling is much faster with hot moulds and thecleaning of the moulds in the hot state can be carried out only with asafety risk due to the risk of burning. Particularly in the case of aso-called hot filling installation with a blow moulding machine and afiller block, this cleaning of the moulds is often a very negativeaspect.

A container production apparatus and a production method for mouldedbodies are known from WO 2008 125216 A2. In this case, a radiationdevice is arranged at or on the blow moulding machine, the radiationbeing directed at least onto one region of the blow moulding machine.

The object of the present invention is therefore to simplify thecleaning of such blow moulding machines. The object of the invention isalso to provide an automated method for cleaning blow moulds.

SUMMARY OF THE INVENTION

An apparatus according to the invention for transforming plasticpreforms into containers comprises at least one blow mould which forms acavity, inside which the plastic preforms can be transformed intocontainers. The apparatus also comprises a pressure application devicefor applying a medium to the plastic preforms in order to expand thelatter against an inner wall of the blow mould delimiting the cavity.The apparatus advantageously also comprises a stretching rod forstretching the plastic preforms in the longitudinal direction thereof,and also an opening and closing mechanism for opening and closing theblow mould. The apparatus also comprises a cleaning device for cleaningregions of the blow mould.

According to the invention, the cleaning device comprises at least afirst cleaning element for cleaning the inner wall of the blow mould,and this cleaning element is arranged at least at times outside the blowmould.

Advantageously, the cleaning device allows an automated cleaning of theblow mould. For example, a special cleaning mode may be provided, inwhich the blow mould or the inner wall thereof is cleaned. However, thepresent invention is also applicable to blow moulding machines whichhave no stretching rod.

It is therefore proposed according to the invention to use a cleaningsystem and in particular a so-called CIP (Cleaning-In-Place) cleaningsystem to clean the inner wall of the blow mould. Particularly duringthe times in which the cleaning element is not carrying out anycleaning, said cleaning element is arranged outside the blow mould. Theopening and closing mechanism is advantageously also used to load a blowmould with new plastic preforms and to remove blow-moulded containersfrom the blow mould.

In one advantageous embodiment, the apparatus comprises a transportdevice which transports the blow moulds along a predefined transportpath. Advantageously, a plurality of blow moulds are arranged on arotatable carrier and particularly preferably on a circular carrier.This is preferably the same carrier on which the blow moulds can also bearranged during normal operation of the apparatus. The apparatusadvantageously has a cleaning mode for carrying out the cleaning of theblow moulds.

The blow moulds are advantageously arranged such as to be movablerelative to the cleaning device. To this end, it is possible that thecleaning devices or cleaning elements are arranged in a stationarymanner along the transport path of the blow moulds in the normaloperating mode. However, it would also be possible that the cleaningdevice together with the blow moulds is arranged on a carrier and thiscarrier transports both the blow moulds and the cleaning elements.

In a further advantageous embodiment, at least one cleaning element is acleaning nozzle which applies a liquid cleaning medium to the innerwall.

Suitable cleaning agents are those substances which can be used to clean(CIP cleaning) the outside and inside of machines and installations inthe beverage-bottling industry. Examples of such cleaning agents aresodium hydroxide (NaOH), acidic cleaning agents based on phosphoricacid, acidic cleaning agents based on nitric acid, disinfecting agentsbased on acetic acid, ozone, hydrogen peroxide, chloralkali cleaningagents, hot water or steam. In addition, chlorine dioxide could also beused as the cleaning agent.

In a further advantageous embodiment, the cleaning device comprises asecond, mechanical cleaning element which can be brought into contactwith the inner wall. This cleaning element may be for example a brushdevice which is advantageously arranged such as to be able to rotate.This second cleaning element is preferably also arranged outside theblow mould in a closed state of the latter. Advantageously, the firstcleaning element can be controlled independently of the second cleaningelement. The first cleaning element and the second cleaning elementpreferably act in different ways on the inner wall of the blow mould.

In a further advantageous embodiment, the mechanical cleaning element isarranged after the cleaning nozzle in the transport direction of theblow moulds. It is thus possible that the inner wall is first sprayedwith the cleaning medium and then cleaned and/or polished by thecleaning brush.

In a further advantageous embodiment, the cleaning element, for examplethe brush, is spaced apart from the cleaning nozzle in the transportdirection of the blow moulds. In this way, in the cleaning mode, apredefined period of time elapses between the application of thecleaning medium to the inner wall and the subsequent polishing with thebrush, so that the cleaning medium is left to act for a certain periodof time. However, it would also be possible that, for example while theblow mould is stationary, firstly a cleaning nozzle and then a cleaningbrush enters the blow mould.

Preferably, transport devices are provided for moving the cleaningnozzles or cleaning brushes. These may be transport devices which movethe nozzles or the brushes for example perpendicular to the longitudinaldirection of the blow mould. However, it would also be possible thatsaid elements are introduced into the blow mould in the longitudinaldirection of the blow mould.

In a further advantageous embodiment, the apparatus comprises arotatable carrier, on which a plurality of blow moulds are arranged.

Advantageously, the apparatus also comprises a rinsing device forrinsing the blow moulds. This rinsing device is in this case preferablyprovided between a cleaning nozzle and a second cleaning element in theform of a polishing means such as a brush. However, it would also bepossible that the rinsing device is provided in the region of the brush,or even after the latter.

The present invention also relates to a method for transforming plasticpreforms into plastic containers, wherein the plastic preforms areexpanded inside a cavity through the application of a medium to formplastic preforms, and wherein this cavity is formed by at least oneinner wall of the blow mould, and the blow mould can be transferred froman open state to a closed state. Furthermore, a cleaning mode isprovided, in which no plastic container is accommodated inside the blowmould and at least one region of the blow mould is cleaned.

According to the invention, the cleaning takes place at least partiallyand preferably entirely in an open state of the blow mould and a firstcleaning element for cleaning the inner wall of the blow mould isarranged at least at times outside the blow mould. This element isprovided outside the blow mould in particular in a conventionaloperating mode, i.e. in a mode other than the cleaning mode. Preferably,this cleaning element is provided outside the blow mould in a closedstate of the latter.

However, such a cleaning element is not provided exclusively for use inblow moulding machines. Cleaning by means of a CIP apparatus (“CIPcleaning”) is possible in particular in apparatuses for treating plasticpreforms and/or plastic containers. The CIP cleaning of the preferentialheating module via an insertable rod or an automaton from outside wouldbe conceivable. In this connection, a preferential heating module isunderstood to mean a device suitable for controlling the temperature ofat least one plastic preform in such a way that it has a temperatureprofile in one direction of expansion. If, for example, the temperatureprofile extends around the circumference, it is possible during asubsequent expansion of the plastic preform to expand hotter regions toa greater extent than cooler regions. It is thus possible in a simplemanner to produce for example plastic containers which have an ovalcross section at least in some parts.

The cleaning of other treatment units by means of a CIP apparatus isalso possible, such as sterilisation apparatuses for example. By way ofexample, the CIP cleaning of an H₂O₂ module (hydrogen peroxidesterilisation module) via an insertable rod or an automaton from outsideis conceivable.

In one advantageous method, the blow mould is opened and a liquidcleaning agent is applied to the inner wall in the open state.

In a further advantageous method, the inner wall is cleaned by amechanical cleaning element in an open state of the blow mould. Thiscleaning by the mechanical cleaning element takes place in particularafter the application of the fluid.

The blow mould is advantageously transported, namely both during theoperating mode and in particular also during the cleaning mode.

In a further advantageous method, the cleaning fluid is left on theinner wall of the blow mould for a predefined period of time in order toact thereon.

Advantageously, a rinsing mode is also provided, in which the inner wallis rinsed. This rinsing mode is advantageously provided after theapplication of the cleaning agent and before or after the polishing orcleaning of the inner wall with the brush or the cleaning element. In afurther preferred method, the brush or the cleaning element is laterallyinserted during this, i.e. in a direction perpendicular to thelongitudinal direction of the blow mould.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and embodiments will emerge from the appendedfigures:

In the figures:

FIG. 1 shows a perspective view of an apparatus for the transformation;and

FIG. 2 shows a schematic view of an installation according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an apparatus for transforming plastic preforms (not shown)into plastic containers (not shown). This apparatus comprises a maincarrier 11, on which a blow mould 2 is arranged in a blow mould carrier3 (in each case shown only partially).

Formed inside the blow mould 2 is a cavity 4, inside which the plasticpreforms are expanded through the application of compressed air to formplastic containers. Furthermore, the apparatus comprises a stretchingrod 12, which is movable here in the longitudinal direction L in orderto stretch the plastic preforms. Reference 22 denotes a first blow mouldhalf and reference 24 denotes a second blow mould half. In addition, theblow mould also has a bottom or a bottom part which closes the cavity 4in the downward direction during operation. Reference 14 denotes apressure application device or blowing nozzle which applies compressedair to the plastic preforms.

FIG. 2 shows a schematic view to illustrate a cleaning procedure. Thisshows in detail a machine in a preferably special cleaning mode. Morespecifically, this is an automatic cleaning process which neverthelesscan be incorporated on machines that are already in development and onmould changing machines that have already been developed by theapplicant. This mould changing device already has the ability to openthe mould carrier automatically and also to loosen appropriate fixingscrews and tighten these again. This arrangement also already allows anautomatic closing of the mould carrier.

For use as a cleaning device, in particular the fixing functions arereplaced by the cleaning function. In this case, the mould is unlockedand opened in a first stage or the region denoted by reference A. Aspray head 16 applies a cleaning agent to the inner wall of the openblow mould 2. For this purpose, this spray head 10 may be moved (arrowP1) by means of a transport or displacement device into the inner regionof the blow mould 2, which is now open, or else can be guided over theinner surface 8 of the blow mould by means of a special device, such asa robotic arm for example, and can spray said surface.

It would also be possible that a plurality of such spray heads areprovided. For example, use could be made of spray heads which are set inrotation by the cleaning medium passing through, and which thus dispensethe cleaning agent in the full circumferential direction. A plurality ofsuch spray heads could also be arranged one above the other in thelongitudinal direction L of the blow moulds 2 shown in FIG. 1.

In the region denoted by reference B, the cleaning agent acts on theinner surface 8 of the blow mould 2 (cf. FIG. 1). It would also bepossible to close the blow mould again in this region, but in theembodiment shown in FIG. 2 the blow mould 2 remains open in this state.In the section denoted by reference C, a second cleaning element 18 isused which mechanically cleans the sprayed inner surface. This may befor example a rotating polishing head which cleans the inner surface. Atthe same time as this polishing process, the rinsing liquid, such asdistilled water for example, may also be applied to the inner surface.However, this application of distilled water could also take place atthe end of the region B, or after the polishing process.

The cleaning element 18 is also moved into the inner region of the openblow mould 2 for cleaning purposes. However, it would also be possiblethat a corresponding cleaning element is moved into the blow mould fromabove or from below. Depending on the geometric dimensions, twopolishing elements in the form of two parallel brushes would also beconceivable, which mechanically clean the inner wall 8.

After the region C, the blow mould is closed again. Reference 15 denotesthe rotating carrier (arrow P2) on which the blow moulds 2 are arranged,and reference 10 denotes the cleaning device in its entirety. Inaddition, the apparatus may have cams (not shown) which bring about theopening and closing of the blow moulds 2. Cams which move the cleaningelements 16 and 18 into the open blow mould and out of the latter mayadditionally also be provided. However, these movements may also bebrought about by electric motors and in particular by servo motors.

By virtue of the mould cleaning according to the invention, there is noneed for manual cleaning which is very complicated in the prior art. Forexample, the moulds must at present be placed into a cleaning fluidduring storage in a mould changing carriage. Furthermore, there is theadvantage that this automatic mould cleaning can be carried out evenwhile the blow moulds are still very hot in parts, which is not possiblein the case of manual cleaning due to the risk of injury to the user.However, these increased temperatures, particularly of the innersurfaces 8, offer the advantage of a possible greater efficiency of thecleaning agent and of the cleaning process per se. Preferably, theapparatus according to the invention has a special cleaning mode, whichmay be provided for example as an interval circuit. Furthermore, removalor opening of the blow moulds by the user is no longer necessary, andthe safety risk is reduced since the protection circuit of the machineremains closed even during the cleaning.

Furthermore, as mentioned above, an increased temperature of the blowmould can be maintained even during the cleaning, or the blow mould mayalso be temperature-controlled or cooled during the cleaning. Thisensures a quicker restart after the cleaning process.

It is pointed out that the cleaning arrangement according to theinvention can also be retrofitted on already existing installations. Asshown in FIG. 2, both the cleaning element 16 or the spray head 16 andthe cleaning element 18 are arranged in a stationary manner relative tothe direction of rotation of the carrier 15. However, it would also bepossible to arrange these elements 16, 18 in a movable manner, forexample on the carrier 15. In a cleaning mode, the individual blowmoulds 2 can be moved (preferably in cycles), so that for example aspecific blow mould remains in a correct position and then the cleaningprocesses are carried out.

All of the features disclosed in the application documents are claimedas essential to the invention in so far as they are novel individuallyor in combination with respect to the prior art.

LIST OF REFERENCES

-   1 apparatus-   2 blow mould-   3 blow mould carrier-   4 cavity-   8 inner surface-   10 cleaning device-   11 main carrier-   12 stretching rod-   14 pressure application device-   15 carrier-   16 first cleaning element, spray head-   18 cleaning element-   22 first blow mould half-   24 second blow mould half-   26 bottom part-   A, B, C region-   L longitudinal direction-   P1, P2 arrows

1-14. (canceled)
 15. An apparatus for transforming plastic preforms intocontainers, comprising at least one blow mould which forms a cavity,inside which the plastic preforms can be transformed into containers,comprising a pressure application device for applying a medium to theplastic preforms in order to expand the latter against an inner wall ofthe blow mould delimiting the cavity, comprising a stretching rod forstretching the plastic preforms in the longitudinal direction (L)thereof, and comprising an opening and closing mechanism for opening andclosing the blow mould, wherein the apparatus comprises a cleaningdevice for cleaning regions of the blow mould, wherein the cleaningdevice comprises at least a first cleaning element for cleaning theinner wall of the blow mould, and this cleaning element is arranged atleast at times outside the blow mould and is movable by a robotic arm.16. The apparatus according to claim 15, wherein the apparatus comprisesa transport device which transports the blow moulds along a predefinedtransport path.
 17. The apparatus according to claim 15, wherein theblow mould is arranged such as to be movable relative to the cleaningdevice.
 18. The apparatus according to claim 15, wherein at least onecleaning element is a cleaning nozzle which applies a liquid cleaningmedium to the inner wall.
 19. The apparatus according to claim 15,wherein the cleaning device comprises a mechanical cleaning elementwhich can be brought into contact with the inner wall.
 20. The apparatusaccording to claim 18, wherein the mechanical cleaning element isarranged after the cleaning nozzle in the transport direction of theblow moulds.
 21. The apparatus according to claim 20, wherein the secondcleaning element is spaced apart from the cleaning nozzle in thetransport direction of the blow moulds.
 22. The apparatus according toclaim 15, wherein the apparatus comprises a rotatable carrier, on whicha plurality of blow moulds are arranged.
 23. The apparatus according toclaim 15, wherein the apparatus comprises a rinsing device for rinsingthe blow moulds.
 24. A method for transforming plastic preforms intoplastic containers, wherein the plastic preforms are expanded inside acavity through the application of a medium to form plastic preforms, andwherein this cavity (is formed by at least one inner wall of a blowmould, and the blow mould can be transferred from an open state to aclosed state, wherein a cleaning mode is provided, in which no plasticcontainer is accommodated inside the blow mould and at least one regionof the blow mould is cleaned, wherein the cleaning takes place in anopen state of the blow mould and a first cleaning element for cleaningthe inner wall of the blow mould is arranged at least at times outsidethe blow mould and is moved by a robotic arm.
 25. The method accordingto claim 24, wherein the blow mould is opened and a liquid cleaningagent is applied to the inner wall in the open state.
 26. The methodaccording to claim 24, wherein the inner wall is cleaned by a mechanicalcleaning element in an open state of the blow mould.
 27. The methodaccording to claim 25, wherein the cleaning fluid is left on the innerwall for a predefined period of time in order to act thereon.
 28. Themethod according to claim 10, wherein a rinsing mode is provided, inwhich the inner wall is rinsed.
 29. The apparatus according to claim 15,wherein the cleaning element has a spray head which is movable by arobotic arm.
 30. The apparatus according to claim 28, wherein the sprayhead is guidable over the inner surface and is spraying the innersurface.
 31. The method according to claim 24, wherein the cleaningelement has a spray head which is moved by a robotic arm.
 32. The methodaccording to claim 31, wherein the spray head is guided over the innersurface and sprays the inner surface.